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Advances in Materials Science and Engineering
Volume 2015, Article ID 148657, 6 pages
Research Article

Microstructure and Mechanical Property of Hot-Pressed Al2O3-Ni-P Composites Using Ni-P-Coated Al2O3 Powders

1Department of Mechanical Engineering, University of Incheon, 12-1 Songdo-dong, Yeonsu-gu, Incheon 406-772, Republic of Korea
2Technology Convergence Center, Incheon Techno Park, Gaetbeol-ro 12, Songdo-dong, Yeonsu-gu, Incheon 406-840, Republic of Korea

Received 18 September 2015; Revised 11 December 2015; Accepted 14 December 2015

Academic Editor: Wenbin Yi

Copyright © 2015 Hyeong-Chul Kim and Jae-Kil Han. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Al2O3-Ni-P composite powders with Ni-P contents of 10.9, 14.4, and 20.4 wt.% were synthesized via the Ni-P electroless deposition process. The as-received Al2O3-Ni-P composite powders were composed of Ni-P particles and Ni-P coating layer. Some Ni-P particles randomly adhered to the Al2O3 powders, and their particle diameter ranged from 5 nm to 20 nm. The thin Ni-P layer had about 5 nm thick amorphous structure and directly bonded with Al2O3 powders. Using the Ni-P-coated Al2O3 powders, a dense Al2O3-Ni-P composite can be successfully obtained using the hot press process at 1,350°C for 1 hour in an Ar atmosphere under an applied pressure of 30 MPa. The hot-pressed Al2O3-15 wt.% Ni-P composite showed excellent material properties. Its relative density, Vickers hardness, and fracture toughness were comparatively high: about 99.1%, 2,360 Hv, and 6 MPa·m1/2, respectively. The fracture surface of the hot-pressed Al2O3-Ni-P composite showed a semiductile mode due to the mixed intergranular and transgranular fracture mode. In particular, the fracture toughness of the hot-pressed Al2O3-15 wt.% Ni-P composite was strongly enhanced by the combined action of the crack branching and the crack deflection.